The topic say it all.

SPOILER!

There is a dangerous building in the temple district. Look at the map, cause I didn't take notice of this building until looking at the map. It is a quite large building.

On your map of the temple district you should have a marker in the NE section that says something like "Guarded Compound". I believe that it can be found there...

... yeah, and when you get there put on your gloves cause it's reputedly the best scripted NPC battle of the game. These guys crank. You'll earn every point.